Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/44—Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/12—Polymerisation in non-solvents
  • C08F2/16—Aqueous medium
  • C08F2/22—Emulsion polymerisation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F292/00—Macromolecular compounds obtained by polymerising monomers on to inorganic materials
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • G03G9/08722—Polyvinylalcohols; Polyallylalcohols; Polyvinylethers; Polyvinylaldehydes; Polyvinylketones; Polyvinylketals
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • G03G9/08726—Polymers of unsaturated acids or derivatives thereof
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/087—Binders for toner particles
  • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
  • G03G9/08791—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by the presence of specified groups or side chains
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/093—Encapsulated toner particles
  • G03G9/09392—Preparation thereof
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components

Definitions

• Metals, metal oxides, pigments, fillers and other inorganic particulates are broadly used in many applications. However, some of these materials tend to agglomerate and are, thus, often coated with, or encapsulated in, polymers. Such coated or encapsulated particles are used in a wide variety of applications such as electro-conductive additives to plastics, toners in electrophotography, pigmented ink, electrophoretic display as well as many other applications. Moreover, coated or encapsulated particles are often charged in order to help the particles to respond to electric field.
• charged particles such as electronic ink materials or electrophoretic display materials are mostly negatively charged.
• having a unidirectional charging mechanism often limits the design of devices. Indeed, as an example, when particles are pigments, the negative charge limits device architecture to have stacked layers in order to accommodate multiple colors. Such architecture often results, thus, in that most of the light incident to the display is scattered by the top layers and, therefore, insufficient light reaches the bottom layer which lead thus to low optical density.
• Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of synthetic organic chemistry, ink chemistry and the like, that are within the skill of the art. Such techniques are explained fully in the literature. The following examples are put forth to provide those of ordinary skill in the art with a complete disclosure and description of how to perform the methods disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C, and pressure is at or near atmospheric. Standard temperature and pressure are defined as 20°C and 1 atmosphere. Unless otherwise indicated, the viscosity is measured at a shear rate of 1 1 .1/sec, is expressed in cps and is measured at a temperature of 25°C.
• approximately 20 wt% should be interpreted to include not only the explicitly recited concentration limits of 1 wt% to approximately 20 wt%, but also to include individual concentrations such as 2 wt%, 3 wt%, 4 wt%, and sub-ranges such as 5 wt% to 15 wt%, 10 wt% to 20 wt%, etc. Unless indicated otherwise, the percentage (%) of components expresses the weight percentage (wt%) of components.
• the present disclosure is drawn to a process for producing a positively charged polymer encapsulated particles, having a size of less than 5 ⁇ , including a positively charged polymer shell surrounding a core of particle.
• the process includes the steps of:
• the polymer shell of the encapsulated particle includes polymers or co-polymers that have a functional group FG;
• the present disclosure relates to positively charged particles, obtained according to the process such as describe herein, that are suitable for use in liquid electrophotographic printing. In yet another embodiment, the present disclosure relates also to positively charged particles obtained according to the process such as describe herein, that are suitable for use in electrophoretic displays.
• the term "encapsulate” or “encapsulated” includes partial to complete encapsulation of a particle with a polymer shell. This can be done by adsorption or by reacting the polymer shell on the surface of the particulate.
• the positively charged polymer encapsulated particle resulting from the process according to the present disclosure, has a size which is between from about 10 nm to about 5 ⁇ in diameter. In another embodiment, the positively charged polymer encapsulated particle, has a size which is between from about 100 nm to about 500 nm in diameter.
• the positively charged polymer encapsulated particle has bulk density ranging from about 0.90 g/cm 3 to about 3 g/cm 3 .
• the polymer-encapsulated particle has a surface dielectric constant ranging from about 1 .5 to about 3.0, at room temperature.
• the positively charged polymer encapsulated particle has a surface dielectric constant ranging from about 2.3 to about 2.8.
• such a positively charged polymer encapsulated particle can have a calculated T g from about -40°C to about 125°C. In one
• the calculated T g can be from about 0°C to about 75°C, and in one aspect, can be from 35°C to about 50°C.
• the positively charged polymer encapsulated particle has a Zeta potential value which is either larger than + 15 mV or less than - 15 mV
• the positively charged polymer encapsulated particle has an average Zeta potential which is either above about + 15 mV or below about - 20 mV.
• the Zeta potential is the potential across the interface of solids and liquids, and more specifically, the potential across the diffuse layer of ions surrounding a charged colloidal particle which is largely responsible for colloidal stability.
• Zeta potentials can be calculated from electrophoretic mobility, namely, the rates at which colloidal particles travel between charged electrodes placed in the dispersion, emulsion or suspension containing the colloidal particles, using a Zetasizer instrument (form Malvern Instrument Corp.).
• the particles can be pigments, quantum dots, colloidal particles or any particulates.
• the particles can be regular or irregular in shape.
• the particle size is in the range of about 0.1 nm to about 500 nm in diameter. In another embodiment, the particle size is in the range of about 1 nm to about 250 nm in diameter.
• particles are quantum dots.
• quantum dot it is meant herein nano-crystalline materials having optical properties upon ultraviolet excitation.
• particles are colloidal particles.
• colloidal particles it is meant herein particles which are typically nano-scale solids suspended in a continuous phase.
• particles are pigments.
• pigment generally includes organic and inorganic pigment colorants, magnetic particles, aluminas, silicas, and/or other ceramics, organometallics or other opaque particles, whether or not such particulates impart color.
• pigment colorants primarily exemplifies the use of pigment colorants, the term “pigment” can be used more generally to describe not only pigment colorants, but other pigments such as organometallics, ferrites, ceramics, etc.
• the pigment is a pigment colorant.
• the pigment is an organic or an inorganic pigment colorant. Pigments that can be used include self-dispersed pigments, dispersant-dispersed pigments, raw pigments, etc.
• Self-dispersed pigments include those that have been chemically surface modified with a charge or with a polymeric group. This chemical modification aids the pigment in becoming and/or substantially remaining dispersed in a liquid vehicle.
• examples include semi-metal and metal particulates, semi-metal oxides and metal oxide particulates, dispersible silicates and glass particulates, ferromagnetic and other magnetic particulates, whether or not such particulates impart color.
• any color or type of pigment can be used, color organic pigments or black carbon pigments are exemplified herein in accordance with embodiments of the present invention.
• the carbon pigment can be almost any commercially available carbon pigment that provides acceptable optical density and print characteristics.
• Carbon pigments suitable for use in the present invention include, without limitation, carbon black, graphite, vitreous carbon, charcoal, and combinations thereof.
• the carbon pigment is a carbon black pigment.
• Such carbon black pigments can be manufactured by a variety of known methods such as a channel method, a contact method, a furnace method, an acetylene method, or a thermal method, and are commercially available from such vendors as Cabot
• organic colored pigments can also be encapsulated in accordance with embodiments of the present invention.
• Exemplary pigments that are suitable for use in accordance with embodiments of the present invention include azo pigments such as azo lake pigments, insoluble azo pigments, and condensed azo pigments; as well as polycyclic pigments such as phthalocyanine pigments, quinacridone pigments, dioxazine pigments, and anthraquinone pigments.
• the particles can be red, green, blue, cyan, yellow, magnet, or black colored pigments.
• the particles can be charged pigment particles.
• the pigments may be white or color, and may be organic or inorganic.
• white pigments include hollow particles, BaSO 4 , ZnO, CaCO3, TiO 2 and the like.
• color pigments include phthalocyanine blue, phthalocyanine green, diarylide yellow, diarylide AAOT yellow, quinacridone, azo, rhodamine, perylene pigment series from Sun Chemical, Hansa yellow G particles from Kanto Chemical, Carbon Lampblack from Fisher and the like.
• particles can be organic or inorganic solid particles.
• inorganic solid particles examples include inorganic pigments such as titanium dioxide, zinc oxide, antimony oxide, magnesium oxide, fly ash, red oxide, yellow oxide, lemon chrome and cobalt blue; powders of metals including titanium, copper, brass, gold and stainless steel; carbonates such as calcium and magnesium carbonates; phosphates such as calcium and lead phosphates; silica and silicates such as clay and glass particles; chromates such as lead chromate; metal salts such as silver chloride; inert filler materials such as titanates and talc; ferrites; aluminum hydrates; and the like.
• inorganic pigments such as titanium dioxide, zinc oxide, antimony oxide, magnesium oxide, fly ash, red oxide, yellow oxide, lemon chrome and cobalt blue
• powders of metals including titanium, copper, brass, gold and stainless steel
• carbonates such as calcium and magnesium carbonates
• phosphates such as calcium and lead phosphates
• silica and silicates such as clay and glass particles
• chromates such as lead
• particles can be powders of metals and metal alloys such as aluminum, cobalt, iron, copper, nickel, chromium, zinc, palladium, silver, ruthenium, platinum, gold, rhodium, lead and alloys of these metals.
• metals and metal alloys such as aluminum, cobalt, iron, copper, nickel, chromium, zinc, palladium, silver, ruthenium, platinum, gold, rhodium, lead and alloys of these metals.
• oxides of such metals particularly magnetic oxides such as iron, nickel, cobalt or alloys thereof, as well as oxides of other elements such as titanium dioxide and silica.
• particles are titanium dioxide. In another embodiment, particles are titanium dioxide having an average diameter in the range from about 0.2 ⁇ to about 0.4 ⁇ . In an embodiment, particles are silica in the form of particles having an average diameter from about 0.005 ⁇ to about 0.2 ⁇ . In another embodiment, particles are magnetic iron oxides of the formula Fe 3 O which are in the form of finely divided magnetic particles. In yet another embodiment, particles are magnetic iron oxides having an average particle diameter in the range from about 0.005 ⁇ to about 0.1 ⁇ .
• the particles are in a first step (a), dispersed in an aqueous solution in view of obtaining aqueous colloidal dispersion of particles.
• the aqueous colloidal dispersion of the particles is prepared by contacting the solid with an aqueous solution of a water-soluble surface active agents or emulsifiers thereby forming a dispersion which contains from about 5 to about 70 weight percent of the solid particles.
• examples of suitable surface active agents or emulsifiers include salts of fatty acids such as potassium oleate, metal alkyl sulfates such as sodium lauryl sulfate, salts of alkyl aryl sulfonic acids such as sodium dodecylbenzene sulfonate, polysoaps such as sodium polyacrylate and alkali metal salts of methyl methacrylate/2-sulfoethyl methacrylate copolymers and other sulfoalkyl acrylate copolymers, and other anionic surfactants such as the dihexyl ester of sodium sulfosuccinic acid; nonionic surfactants such as the nonionic condensates of ethylene oxide with propylene oxide, ethylene glycol and/or propylene glycol; and cationic surfactants such as alkylamine-guanidine polyoxyethanols.
• fatty acids such as potassium oleate
• such surface active agents or emulsifiers are employed in amounts sufficient to provide a stable dispersion of the solid particles in water.
• such surface active agents are employed in concentrations in the range of from about 0.2 to about 10, and, in yet another embodiment, in the range of from about 1 to about 6, weight percent based on the aqueous phase.
• the particles are mixed with monomers either before or either after the dispersion step (a).
• the dispersion step is done by dispersing the particles or the mixture particles/monomers into a liquid aqueous medium.
• the aqueous dispersion of solid particles is combined with the water-immiscible monomers to form an emulsion by normal mixing procedures, for example, by passing both the dispersion and monomers through a high shear mixing device such as a Waring blender, homogenizer or ultrasonic mixer.
• the mixture of monomers is added continuously to the aqueous dispersion of solid particles during the polymerization step.
• the monomers are in the form of an aqueous emulsion of monomers which emulsion is maintained by water-soluble monomers and/or water-soluble emulsifiers such as described hereinbefore.
• the aqueous emulsion of particles and water-immiscible monomers can be prepared by adding colloidal particles to an existing aqueous emulsion of monomers.
• the aqueous phase is present in a proportion sufficient to be the continuous phase of the emulsion.
• the solid particles are present in proportions sufficient to provide the matrix particulate, with the desired characteristics, e.g., magnetic properties, pigmentation, etc.
• the water-immiscible monomers are present in proportion sufficient to enclose or encapsulate the particulates when polymerized and sufficient emulsifiers and/or surface active agents are present in order to provide an aqueous colloidal emulsion which is sufficiently stable to be subjected to emulsion polymerization conditions.
• the emulsion contains from about 0.1 to about 25 weight percent of solid particles.
• the emulsion contains from about 1 to about 30 weight percent of monomers and a remaining amount of the aqueous phase including emulsifiers (surfactants), catalyst and the like.
• the present disclosure relates to a method of encapsulating particles including the step (a) of dispersing particles in an aqueous solution to form particles dispersion, adding monomers, in the step (b), either before or after the dispersion step (a), and polymerizing the monomers to form encapsulated particles in the step (c).
• the present disclosure relates to a method of encapsulating particles including the step of mixing particles with monomers in view of forming a paste or a paste-like solid; dispersing the paste in an aqueous solution to form a dispersion, and polymerizing the monomers in the presence of particles to form encapsulated particles.
• the present disclosure relates to a method of encapsulating particles including the step of dispersing particles in an aqueous solution to form particles dispersion; adding monomers to the dispersion and polymerizing the monomers, in the presence of particles, to form encapsulated particles.
• the polymerization step (c) is carried out in the presence of a radical initiator. It is believed that such initiator helps generating the polymer on the surface of the particles.
• a radical initiator helps generating the polymer on the surface of the particles.
• water insoluble initiators are added to the monomer mixture to avoid phase separation.
• water insoluble initiators are added to the mixture, for easy handling, just before the beginning of the polymerization step.
• the polymerization step (c) is carried out in the presence of an initiator at temperatures in the range of from about 50°C to about 90°C.
• the emulsion can be agitated during the polymerization period in order to maintain adequate feed transfer.
• the concentration of initiators is in the range from about 0.005 to about 8 weight percent, in another embodiment, from about 0.01 to about 5 weight percent, based on total amount of monomers.
• Such initiators can be water miscible or immiscible radical generators, including diazocompounds, peroxides and redox initiators.
• the initiator can be any radical initiator such as a peroxygen compound, an azo catalyst, ultraviolet light and the like.
• suitable catalysts include inorganic persulfate compounds such as sodium persulfate, potassium persulfate, ammonium persulfate; peroxides such as hydrogen peroxide, t-butyl hydroperoxide, dibenzoyl peroxide and dilauroyi peroxide; azo catalysts such as azobisisobutyronitrile, and other common free-radical generating compounds.
• redox catalyst composition can be employed wherein the polymerization temperature ranges from about 25°C to about 80°C.
• exemplary redox catalyst compositions include a peroxygen compound, in an embodiment, potassium persulfate or t-butyl hydroperoxide and a reducing component such as sodium metabisulfite and sodium formaldehyde hydrosulfite.
• the polymerization process is carried out using a water-soluble
• polymerization initiator such as potassium persulfate, sodium persulfate, ammonium persulfate, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2- methylpropionamidine)dihydrochloride, and hydrogen peroxide.
• polymerization initiators may be used alone, or two or more kinds of them may be used in
• monomers are added to the aqueous dispersion of particles for the polymerization step (c).
• the monomers are hydrophobic monomers.
• the monomers are organic monomers.
• the monomers are acrylic or methacrylic monomers.
• the monomers are linear, branched or cyclic aliphatic acrylate monomers. Examples of linear, branched or cyclic aliphatic acrylate monomers include ethyl, propyl, iso butyl, butyl, tertiary butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, octadecyl, 2- ethylhexyl, lauryl, cyclohexyl acrylates or t-butylcyclohexyl monomers.
• the monomers are functional monomers such as 2- hydroxylethyl, 2-hydroxyl propyl, 2-hydroxylbutyl, dimethylaminoethyl, glycidyl, butanediol, 2-carboxylethyl, 2-ethoxyethyl, di(ethylene glycol methyl ether, ethylene glycol methyl ether, ethylene glycol phenyl ether, 2-(4-benzoyl-3- hydroxyphenoxy)ethyl, 2-(dialkylamino)ethyl, 2-(dialkylamino)propyl, 2- [[(butylamino)carbonyl]-oxy]ethyl, 2-hydroxyl-3-phenoxypropyl, 3,5,5-trimethylhexyl, 3- (trimethyloxysilyl)propyl, 3-sulfopropyl, di(ethylene glycol)-2-ethylhexyl ether, dipentaerythritol penta/hexa,
• the monomers of the present disclosure include a mixture of hydrophobic and acidic monomers.
• the hydrophobic monomers are present in an amount representing up to 99 wt% of the total amount of monomers forming the polymer shell.
• the hydrophobic monomers are present in an amount representing from about 70 wt% to about 98 wt% of the total amount of monomers forming the polymer shell.
• hydrophobic monomers contain free-radically polymerizable vinyl groups.
• the hydrophobic monomers are acrylate, methacrylate or other vinyl-containing monomers such as styrene.
• hydrophobic monomers include methyl methacrylate, methyl acrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, octadecyl methacrylate, isobornyl methacrylate, vinyl acetate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2- ethylhexyl acrylate, lauryl acrylate, octadecyl acrylate, isobornyl acrylate, styrene, methylstyrene,
• Suitable acidic monomers include acrylic acid, methacrylic acid, methacryloyloxyethyl succinate or phosphate, itaconic acid, maleic acid, vinyl benzoic acid, styrene sulfonate sodium salt monomers, derivatives thereof and combinations thereof.
• the acidic monomers may provide stability to the polymer shell of the encapsulated particles so that they are stable in water. More particularly, the acidic monomers incorporate charges to the polymer shell, which contribute to their stability. The charge of particle may be further enhanced by raising the pH of the medium on which the encapsulated particle will be established to convert -COOH functional groups of the acid into a salt form. In an embodiment, other monomers, that can increase the stability, might be present in the polymer shell of the encapsulated particle, which include acrylamide and vinylpyrrolidone monomers.
• the concentration of monomer components is from 0.5% to 25% by weight, based on the total weight of the aqueous solution. In another embodiment, the concentration of monomer components is from 5% to 10% by weight, based on the total weight of the aqueous solution.
• the concentration of monomer components is lower than 5% by weight, the polymerization reaction cannot rapidly proceed, so that a sufficiently high polymerization rate cannot be obtained.
• the concentration of monomer components is higher than 10% by weight, particles made only of a polymer may easily be produced at a place other than the surfaces of particles (i.e., in a solvent), so that a polymer layer cannot effectively be formed on the surface of each particles.
• the total amount of monomer components is the total amount of monomer components which have been added to a solvent until the completion of a polymerization reaction.
• the mixture has a monomer to particle ratio of from about 0.25:1 to about 5:1 .
• the monomer to particle ratio is from about 0.5:1 to about 3:1 .
• the monomer to particle ratio is from about 1 :1 to about 3:1 .
• the monomers described herein can be of any number of compounds and are capable of forming a polymer or a co-polymer having a functional group "FG".
• the monomers described herein can be polymerized in situ to form polymers or co-polymers that have a basic or a neutral functional group "FG".
• the polymerization step (c) results in polymer encapsulated particles wherein the polymer shell of the encapsulated particles includes a polymer or co-polymer that has a specific basic or neutral functional group FG.
• the specific functional group FG represents any functional group that will interact with a charge director to give positive charge to the particle surfaces, or any functional group that will absorbs the positively charged micelles to the particle surfaces.
• the mixture of monomers encompass between about 1 and about 15 weight percent of monomers capable of forming polymer containing FG group, based on the total amount of monomers forming the encapsulation layer.
• the monomers are selected from the group consisting of N- vinyl amide monomers, heterocyclic vinyl amine monomers, aminoacrylate and methacrylate monomers, acrylamide monomers and derivatives.
• N-vinyl amide monomers examples include N-methyl N-vinyl acetamide, N- vinyl acetamide, N-vinyl formamide and N-vinylmethacetamide.
• N-vinyl amide monomers examples include also N-vinyl cyclic amide, such as N-vinylpyrrolidone and N- vinyl-3-morpholinone monomers.
• heterocyclic vinyl amine monomers examples include N-vinylpyridine, N-vinyloxazolidine, N-vinylpyrimidine, N-vinylpyridazine, N- vinyl-1 ,2,4-triazine, N-vinyl-1 ,3,5-triazine, N-vinyl-1 ,2,3-triazine, N-vinyl-triazole, N- vinyl-imidazole, N-vinylpyrrole and N-vinylpyrazine.
• aminoacrylate and methacrylate monomers include ⁇ , ⁇ -dimethylaminoethyl methacrylate, N,N-dimethyl- aminoethyl acrylate, ⁇ , ⁇ -dimethylaminopropyl methacrylate, N,N-dimethylaminopropyl acrylate, N,N-dimethylacrylamide, ⁇ , ⁇ -dimethylmethacrylamide, N,N-dimethyl-amino- ethylacrylamide, ⁇ , ⁇ -dimethyl-amino-ethylmethacrylamide, N,N-dimethyl-amino- propylacrylamide and ⁇ , ⁇ -dimethyl-amino-propyl-methacrylamide monomers.
• acrylamide monomers include N-alkyl acrylamide, N-aryl acrylamide and N-alkoxyalkyl acrylamide monomers, as such N-methyl acrylamide, N-ethyl
• the functional group "FG" is either a basic or a neutral functional group.
• basic functional groups can be, but are not limited to, trialkyamine R ⁇ N-, wherein F ⁇ R 2 can be, independently, any alkyl or branched alkyl groups, which include, but are not limited to, hydrogen, methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, n-octyl, n-decyl, n-dodecyl and n-tetradecyl groups.
• the functional group FG is a functional group selected from the group consisting of amine, substituted amine, substituted or unsubstituted pyrrolidine, substituted or unsubstituted 2-pyrroline, substituted or unsubstituted piperidine, substituted or unsubstituted pyridine, substituted or unsubstituted
• examples of functional group FG include alkylated alcohols or branched alkylated alcohols.
• the functional group FG is an alcohol containing monomer, such as acrylate and methacrylate monomer.
• the functional group FG is ethylene glycol containing acrylate and methacrylate monomer or polyethylene glycolated methacrylates monomer.
• the functional group FG is an alcohol containing monomer such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropoyl acrylate, hydroxypropyl methacrylate, 3-hydroxypropyl-1 -methyl acrylate, 3- hydroxypropyl-1 -methyl methacrylate, 4-hydroxybutyl acrylate or 4-hydroxybutyl methacrylate monomer.
• Examples of functional group FG include ethylene glycol containing acrylate and methacrylate monomer such as polyethylene glycolated acrylate, polyethylene glycoldi(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol
• functional group FG examples include polyethylene glycolated methacrylate monomer such as methylacrylamide glycolate methylether, polyethylene glycol mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, octoxypolyethylene glycol
• the functional group FG can be the combinations of two or more of the above mentioned monomer compounds.
• the polymerization step (c) results in a polymer encapsulated particle which includes a particle core and a polymer shell.
• the polymer shell contains polymers or co-polymers that have a functional group FG.
• the percentage of FG group presents on the polymer shell of the encapsulated particle represents from about 0.1 % to about 20%, in another
• the polymer-encapsulated particle includes a particle core and a polymer shell, such polymer shell includes a polymer or a copolymer that has, as an example, substituted amines, alkylated alcohols or branched alkylated alcohols as FG groups.
• polymer shell it is meant herein a layer of polymer or co-polymer that is deposited on or attached to the surface of a particle, or alternatively, is attached to an intermediate bridging layer which is deposited on the surface of the particle. This polymer shell can be attached or deposited on the particle or on a bridging layer deposited on the particle. If an environmentally sensitive bridging layer is used, once the polymer encapsulation shell or layer is formed, the change of the environmental conditions that brought about the formation of the bridging layer is often of little consequence, and the polymer encapsulation shell acts to protect the bridging layer from becoming substantially resolubilized.
• the polymer encapsulation shell is applied as a mixture of monomers, and then once on the surface of the particle (or bridging layer), the monomers are polymerized and newly polymerized monomers form the polymer encapsulation shell.
• the thickness of the polymer shell can be of any suitable thickness. However, in an embodiment, the polymer shell has an average thickness ranging from about 2 nm to about 100 nm. In another embodiment, the polymer shell has an average thickness ranging from about 20 nm to about 80 nm. Suitable polymers can have any weight average molecular weight that is functional, but in one embodiment, the average molecular weight is from 5,000 Mw to 2,000,000 Mw. In another embodiment, the average molecular weight is from 25,000 Mw to 500,000 Mw. In an embodiment, the polymer shell of the present invention is prepared by mixing monomers together to form a monomer mixture and then polymerizing such mixture.
• the resulting emulsion polymerization can be withdrawn from the polymerization vessel and the obtained polymer encapsulated particles emulsions are directly dispersed with surfactants and charge directors, in a step (d), in view of obtaining positively charged encapsulated particles dispersion.
• the non-reacted monomers and other volatiles are removed to form a concentrated emulsion containing polymer encapsulated particles. Such concentrated emulsion is then dispersed with surfactants and charge directors in view of obtaining positively charged encapsulated particles dispersions.
• the matrix particulate, containing polymer encapsulated particles can be separated from the aqueous continuous phase of the dispersion by conventional means such as drying under vacuum.
• the dried matrix particulate containing polymer encapsulated particles contains, in an embodiment, from about 1 to about 70 weight percent of solid particles and from about 99 to about 30 weight percent of polymer matrix. Such dried matrix particulate containing polymer encapsulated particles is then dispersed with surfactants and charge directors in view of obtaining positively charged encapsulated particles dispersion.
• the process for producing polymer encapsulated particles according to the present disclosure encompass as a final step (d), the step of dispersing the encapsulated particles, including a polymer shell with FG group, with surfactants and charge directors in view of obtaining positively charged encapsulated particles dispersion.
• the resulting polymer encapsulated particles are freeze dried and re-dispersed in a non-aqueous solution containing dispersants and charge directors.
• the charge director can be defined herein as any
• amphiphilic molecule that can form reversed micelle in non-polar solvents, such as hydrocarbon solvents, and gives charge to particle surface.
• the charge director gives positively charge to the encapsulated particle.
• the charge director may form a micelle structure which is physically associated, but not chemically associated, by hydrophobic bonding with the particle to provide at least part of the particle charge.
• the charge director has the benefit of providing a negative charge to the polymer encapsulated particle, resulting thus in a polymer encapsulated particle which is negatively charged.
• the charged polymer encapsulated particle will thus be switchable by an electric field.
• charge directors may be polymeric or non-polymeric in nature and may also be ionic or non-ionic, including ionic surfactants such as Aerosol OT, sodium dodecylbenzene sulfonate, metal soap, calcium petronate, OLOA ® 1200 (from Chevron Oronite Company), Emphos ® D-70-30C (a phosphated mono/diglyceride from Witco Chemical Co.), Solsperse 17000 (a polymeric dispersant from Lubrizol Inc.), Span surfactants (from ICI Americas Inc.), polybutene succinimide, maleic anhydride copolymers, vinylpyridine copolymers, vinylpyrrolidone copolymers (such as Ganex from International Specialty Products), acrylic or methacrylic acid copolymers, ⁇ , ⁇ -dimethylaminoethyl methacrylate or acrylate copolymers or the like.
• ionic surfactants such as Aerosol OT, sodium do
• charge directors may be organic acid metal salts consisting of polyvalent metal ions and organic anions as the counterion.
• suitable metal ions include Ba(l l), Ca(l l), Mn(l l), Zn(l l), Zr(IV), Cu(l l), Al(l l l), Cr(l l l), Fe(l l), Fe(l l l), Sb(l l l), Bi(l l l), Co(l l), La(l l l), Pb(l l), Mg(l l), Mo(l ll), Ni(ll), Ag(l), Sr(ll), Sn(IV), V(V), Y(l l l), and Ti(IV).
• Non-limiting examples of suitable organic anions include carboxylates or sulfonates derived from aliphatic or aromatic carboxylic or sulfonic acids.
• aliphatic fatty acids are stearic acid, behenic acid, neodecanoic acid, diisopropylsalicylic acid, abietic acid, naphthenic acid, octanoic acid, lauric acid, tallic acid, and the like.
• charge directors are polymers or copolymers having nitrogen-containing monomer, quaternary ammonium block copolymers, lecithin, basic metallic petronates such as basic barium petronate, basic calcium petronate, and basic sodium petronate, metal naphthenate compounds, and polyisobutylene succinimide available as OLOA ® 1200 (from Chevron Oronite).
• nitrogen-containing monomer examples include (meth)acrylates having an aliphatic amino group, vinyl monomers having nitrogen- containing heterocyclic ring, cyclic amide monomers having N-vinyl substituent, (meth)acrylamides, aromatic substituted ethlylenic monomers having nitrogen- containing group, nitrogen-containing vinyl ether monomers, etc.
• examples of charge directors include a copolymer which is soluble in a hydrocarbon carrier liquid and which contain a monomer such as hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl(meth)acrylate, vinyl laurate, vinyl stearate, benzyl (meth)acrylate and pheny (meth)acrylate.
• a monomer such as hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acryl
• charge directors are lecithin, basic metallic petronate and polyisobutylene succinimide.
• the charge director is a mixture of different charge directors and contains, as an example, 30 parts by weight lecithin, 30 parts by weight Basic Barium Petronate (BBP) and 6 parts by weight isopropylamine dodecylbenzesulfonate (ICI G3300B) as a stabilizer.
• BBP Basic Barium Petronate
• ICI G3300B isopropylamine dodecylbenzesulfonate
• the charge directors are polyisobutylene succinimide amines.
• Example of polyisobutylene succinimide amine includes OLOA®1 1000 (available from Chevron Oronite).
• the charge directors are ionizable charge directors that can disassociate to form charges such as sodium di-2- ethylhexylsulfosuccinate or dioctyl sulfosuccinate (AOT).
• the charge directors are zwitterions charge directors such as lecithin.
• the charge directors are non-chargeable and neutral charge directors, which cannot disassociate or react with acid or base to form charge such as fluoro- surfactants.
• polymer encapsulated particles including FG groups are dispersed in a solution containing charge directors.
• the presence of such charge directors results in the formation of positively charged micelles (CM+).
• CM+ positively charged micelles
• Such encapsulated particles, including FG groups interact with positively charged micelles (CM+) in view of forming positively charged polymer encapsulated particles dispersion. Without being linked by any theory, it is believed that such positively charged micelles are adsorbed to the surface of polymer encapsulated particles.
• charged micelles As charged micelles (CM+), it is meant herein positively charged micelles formed from disproportionation reaction of micelles, which in turn are formed by charge directors.
• charged micelles are positively charged OLOA® micelles, i.e., micelles formed by the addition of OLOA®1 1000 (available from Chevron Oronite).
• OLOA®1 1000 available from Chevron Oronite
• the resulting positively charged polymer encapsulated particles are dispersed in solvent, such as for example, Isopar- L® (available for Exxon).
• solvent such as for example, Isopar- L® (available for Exxon).
• such final dispersion includes also surfactants.
• the surfactants used herein are surfactants that can be soluble or partially soluble in solvents such as isoparaffinic solvents (such as Isopar-L® or Isopar- G®). Such surfactants allow charged polymer encapsulated particles to be dispersed and/or stabilized in a solvent medium.
• such surface active agents are employed in concentration in the range of from about 0.2 to about 10 weight percent; in another embodiment, in the range of from about 1 to about 6 weight percent based on the total weight of the dispersion.
• surfactants examples include hyperdispersants such as
• Others examples include dispersants, available from BYK Inc., such as BYK®-1 10, BYK®-163, BYK®-170, BYK®-180.
• Others examples include dispersants, available from Evonik Industries AG, such as Tego®Dispers 630,
• Tego®Dispers 650, Tego®Dispers 651 , Tego®Dispers 655, Tego®Dispers 685 and Tego®Dispers 1000 include dispersants, available from Aldrich Inc., such as Span® 20, Span® 60, Span® 80 and Span® 85.
• the process for producing positively charged polymer encapsulated particles includes as a first step, mixing particles with monomers and with radical initiators.
• the process includes the steps of, firstly, mixing colored pigments with acrylic monomers and with radical initiators.
• the resulting mixture is then submitted to a mechanical mixing.
• such mixing step is done in an aqueous composition containing from 1 to 80 weight percentage of dispersants and/or surfactants.
• the resulting dispersion is then allowed to pass through a high pressure micro-flu id izer and is then cooled until the desired dispersion stability is achieved.
• the solution is collected in a chemical reactor equipped with a stirring mechanism and a reflux condenser.
• the reactor can be purged with inert gas prior to thermal initiation at a temperature ranging between 50°C to 90°C for 5 to 14 hours or until the polymerization is complete.
• the stirring is stopped and the solution is allowed to drain through a 10 to 100 micron screen into a storage bottle, as an example.
• the final solution is then subject to lypholization to remove water.
• the obtained powder is redispersed in appropriate hydrocarbons solvent such as Isopar-L ® or Isopar-G ® (isoparaffinic solvent available for Exxon) or other appropriate organic medium, with appropriate charge directors and with additional surfactants by milling, microfluidizing or ultrasonic techniques.
• appropriate hydrocarbons solvent such as Isopar-L ® or Isopar-G ® (isoparaffinic solvent available for Exxon) or other appropriate organic medium, with appropriate charge directors and with additional surfactants by milling, microfluidizing or ultrasonic techniques.
• a particle (1 ) is dispersed in an aqueous solution containing monomers and initiators. Such particle (1 ) is then polymerized in surface with polymer or co-polymer containing a function group FG. Such polymerizing step result thus in a polymer encapsulated particle (2) including a particle core and a polymer shell with function group FG. The polymer encapsulated particle (2) is then dispersed with appropriate surfactants and with appropriate charge directors in view of obtaining a positively charged polymer encapsulated particle (3) in dispersion in the liquid medium.
• the polymer encapsulated particle (2) containing functional group FG on the surface of encapsulated particle, is dispersed in an solution containing charge directors in the form of charged micelles (CM).
• CM charged micelles
• Such polymer encapsulated particle, containing functional group FG interacts with charged micelles and results, thus, in a positively charged polymer encapsulated particle (4).
• the positively charged particles obtained according to the above disclosed process are suitable for many applications.
• positively charged encapsulated particles are suitable for inkjet compositions, electrophotographic printing compositions and electrophoretic display applications.
• the positively charged encapsulated particles are suitable for use in liquid electrophotographic printing and electrophoretic display. In an embodiment, when used in electrophoretic display, the positively charged
• encapsulated particles obtained according to the process described herein are dispersed in, at least, one liquid system.
• composition the positively charged encapsulated particles obtained according to the process described herein, are used as pigmented toner particles and are dispersed in carrier liquid of liquid toners.
• the positively charged encapsulated particles when used in liquid electrophotographic inks, are in the form of positively charged CMYKW (cyan, magenta, yellow, black and white) pigments.
• CMYKW cyan, magenta, yellow, black and white
• Example 1 formulation of positively charged blue pigments suspension
• a phthalocyanine blue pigment (Heliogen® Blue D7079 pigment, from BASF) are mixed with 40 g of an acrylic monomer mixture containing styrene, hexyl acrylate, methylmethacrylic acid and ethylene glycol dimethacrylate monomers, in the ratio of 20/73/6/1 , and with 0.25 g of azobisisobutylnitrile (radical initiator) in an one liter Erlenmeyer flask.
• the resulting mixture is agitated with the aid of a magnetic stir bar at 300 rpm, in a 500 ml_ aqueous solution containing from 3 g. of sodium dodecylsulfate and 2 g.
• the resulting dispersion is, then, passed through a high pressure micro-flu id izer for 30 minutes, at 240 mL/min, at 80 psi gauge pressure.
• the dispersion is then cooled at a temperature ranging between 0°C and 10°C in view of obtaining a stable dispersion.
• the solution is collected in a chemical reactor equipped with a stirring mechanism and a reflux condenser. The reactor is then purged with inert gas prior to thermal initiation at a temperature of about 60°C for about 10 hours. When the solution temperature has reached a temperature which is below 30°C, the stirring is stopped and the solution is allowed to drain through a 50 micron screen.
• the water is then removed by lypholization.
• the resulting powder is, then, redispersed in lsopar-L®with appropriate charge director (lecithin) and with additional surfactant (Tego®Dispers 630available from Evonik Industries AG).
• Such dispersion is done by ultrasonic techniques, in view of obtaining a solution containing between about 2 and about 10 wt% of particles and about 2 and about 6 wt% of surfactants.
• the obtained positively charged encapsulated particles are in the form of a dispersion of positively charged encapsulated blue pigments.
• the size of the obtained particles is of about 900 nm.
• the zeta potential of the obtained particles is of about +16 mV.
• the positively charged encapsulated blue pigments are responsive to external electric field. Zeta potential of the charged encapsulated particles is measured in lsopar®L, using Zetasizer (Nano Series) Model ZEN3600, supplied by Malvern Instruments.
• Example 2 Formulation of positively charged black pigments suspension
• a pigment (Degussa® XPB-306) is added 10 mL of acrylic monomers containing 200 mg of azobisisobutylnitrile, 25 ⁇ _ of dodecylmercaptan and Solsperse®3000 dispersant (0.1 %). The mixture is then blended thoroughly into a paste and is subsequently incorporated into a surfactant solution.
• surfactant solution is composed of water (280 mL), disulfonate surfactant (2%) and of an ethyoxylated nonionic surfactant (3.6%).
• the incorporation step is done by
• the homogenous dispersion is thus collected into a reaction vessel equipped with a stirring mechanism, a water condenser and an inert gas inlet.
• the polymerization of monomers is processed at 85°C overnight.
• the reaction mixture is allowed to cool to room temperature and screened with a 50 micro sieve into a storage bottle to afford 250 mL of encapsulated carbon black pigments.
• the pH of the composition containing the encapsulated carbon black pigments is further adjusted to pH 9 - 10 by addition of 2M potassium hydroxide.
• a mixture containing encapsulated carbon black pigments (3%), charge director OLOA®1 1000 (3%) and Solsperse®8000 dispersant (1 %) is mixed in lsopar®L (available for Exxon) solvent and is dispersed by milling techniques.
• the positively charged encapsulated particles obtained are positively charged encapsulated black pigments in dispersion.
• the size of the obtained particles is of about 345 nm.
• the zeta potential of the obtained particles is of about + 23.8 mV.
• the positively charged encapsulated black pigments present a nice device switching behavior in in-plane testing cell.
• Example 3 Formulation of positively charged cyan pigments suspension
• a pigment Heliogen®Blue D7086 pigment, from BASF
• acrylic monomers containing 200 mg of azobisisobutylnitrile, 25 ⁇ of dodecylmercaptan and Solsperse®3000 dispersant (0.1 %).
• the mixture is then blended thoroughly into a paste and is subsequently incorporated into a surfactant solution.
• surfactant solution is composed of water (280 mL), disulfonate surfactant (2%) and of an ethyoxylated nonionic surfactant (3.6%).
• the incorporation step is done by microfluidization at 3.3kpsi.
• the homogenous dispersion is thus collected into a reaction vessel equipped with a stirring mechanism, a water condenser and an inert gas inlet.
• the polymerization of monomers is preceded at 85°C
• the reaction mixture is allowed to cool at room temperature and screened with a 50 micro sieve into a storage bottle to afford 250 ml_ of encapsulated carbon black pigments.
• the pH of the composition containing the encapsulated carbon black pigments is further adjusted to pH 9 - 10 by addition of 2M of potassium hydroxide. Then, a mixture containing the encapsulated cyan pigment suspension (3%), charge director OLOA ® 1 1000 (3%) and
• Solsperse ® 19000 dispersant (1 %) (from Lubrizol Advanced Materials Inc.) is mixed in a hydrocarbon solvent (lsopar ® L available for Exxon) and dispersed by milling techniques.
• the positively charged encapsulated particles obtained are in the form of positively charged encapsulated cyan pigments suspension.
• the size of the obtained particles is of about 890 nm.
• the zeta potential of the obtained particles is of about + 16.1 mV.

Applications Claiming Priority (1)

Publications (3)

Family

ID=43876395

Family Applications (1)

Country Status (4)

Families Citing this family (9)

Citations (4)

Family Cites Families (7)

• 2009
  • 2009-10-16 EP EP09850475.6A patent/EP2488300B1/de not_active Not-in-force
  • 2009-10-16 US US13/498,739 patent/US20120187346A1/en not_active Abandoned
  • 2009-10-16 WO PCT/US2009/060958 patent/WO2011046561A1/en active Application Filing
• 2010
  • 2010-09-16 TW TW099131425A patent/TW201126246A/zh unknown

Patent Citations (4)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events